Researchers at Northwestern University have come up with an extremely high-performing thermoelectric material that may be the most efficient yet at converting waste heat into electricity.

Thermoelectric systems generate electricity by using a temperature gradient. When one side of special material is heated, it can cause electrons to start moving from the warmer side to the cooler side, generating an electric current as a result. By tapping into this technology, scientists hope that one day they will be able to recycle energy that would otherwise be wasted as heat in electronics, power plants, and engines.

In thermoelectrics, the efficiency of waste heat conversion is expressed by its “figure of merit,” or ZT. The higher the number, the better the conversion rate, and in this recent breakthrough, the scientists claim to have hit a record ZT of 3.1.

As reported by New Atlas, the key was a material called tin selenide, which the team purified and made it in a polycrystalline form. After a few tests and tweaks, the team found the material to possess all the necessary properties to become a viable material for converting waste heat to electricity.

“This opens the door for new devices to be built from polycrystalline tin selenide pellets and their applications explored,” said study author Mercouri Kanatzidis. “These devices have not caught on like solar cells, and there are significant challenges to making good ones. We are focusing on developing a material that would be low cost and high performance and propel thermoelectric devices into more widespread application.”

Study source: Nature Materials — Polycrystalline SnSe with a thermoelectric figure of merit greater than the single crystal